Nov 082018

Today is the birthday (1656 [O.S. 29th October]) of Edmond Halley FRS, an English astronomer, geophysicist, mathematician, meteorologist, and physicist, known for the comet named after him, whose periodicity he accurately calculated.

Halley was born in Haggerston, in east London. His father came from a Derbyshire family and was a wealthy soap-maker in London. As a child, Halley was very interested in mathematics. He studied at St Paul’s School where he developed his initial interest in astronomy, and from 1673 at The Queen’s College, Oxford. While still an undergraduate, Halley published papers on the Solar System and sunspots. At Oxford, Halley was introduced to John Flamsteed, the Astronomer Royal. Influenced by Flamsteed’s project to compile a catalog of northern stars, Halley proposed to do the same for the Southern Hemisphere.

In 1676, Halley visited the south Atlantic island of Saint Helena and set up an observatory with a large sextant with telescopic sights to catalogue the stars of the Southern Hemisphere. While there he observed a transit of Mercury across the Sun, and realized that a similar transit of Venus could be used to determine the absolute size of the Solar System. He returned to England in May 1678. In the following year he went to Danzig (Gdańsk) on behalf of the Royal Society to help resolve a dispute. Because astronomer Johannes Hevelius did not use a telescope, his observations had been questioned by Robert Hooke. Halley stayed with Hevelius and he observed and verified the quality of Hevelius’ observations. In 1679, Halley published the results from his observations on St. Helena as Catalogus Stellarum Australium which included details of 341 southern stars. These additions to contemporary star maps earned him comparison with Tycho Brahe: e.g. “the southern Tycho” as described by Flamsteed. Halley was awarded his M.A. degree at Oxford and elected as a Fellow of the Royal Society at the age of 22. In September 1682 he carried out a series of observations of what became known as Halley’s Comet, though his name became associated with it because of his work on its orbit and predicting its return in 1758 (which he did not live to see).

In 1686, Halley published the second part of the results from his Saint Helena expedition, a paper and chart on trade winds and monsoons. The symbols he used to represent trailing winds still exist in most modern-day weather chart representations. In this article he identified solar heating as the cause of atmospheric motions. He also established the relationship between barometric pressure and height above sea level. His charts were an important contribution to the emerging field of information visualization.

Halley spent most of his time on lunar observations, but was also interested in the problems of gravity. One problem that attracted his attention was the proof of Kepler’s laws of planetary motion. In August 1684, he went to Cambridge to discuss this with Isaac Newton, much as John Flamsteed had done four years earlier, only to find that Newton had solved the problem, at the instigation of Flamsteed with regard to the orbit of comet Kirch, without publishing the solution. Halley asked to see the calculations and was told by Newton that he could not find them, but promised to redo them and send them on later, which he eventually did, in a short treatise entitled, “On the motion of bodies in an orbit.” Halley recognized the importance of the work and returned to Cambridge to arrange its publication with Newton, who instead went on to expand it into his Philosophiæ Naturalis Principia Mathematica published at Halley’s expense in 1687. Halley’s first calculations with comets were thereby for the orbit of comet Kirch, based on Flamsteed’s observations in 1680-1. Although he was to accurately calculate the orbit of the comet of 1682, he was inaccurate in his calculations of the orbit of comet Kirch. They indicated a periodicity of 575 years, thus appearing in the years 531 and 1106, and presumably heralding the death of Julius Caesar in a like fashion in  (45 BCE). It is now known to have an orbital period of circa 10,000 years.

In 1691, Halley built a diving bell, a device in which the atmosphere was replenished by way of weighted barrels of air sent down from the surface. In a demonstration, Halley and five companions dived to 60 feet (18 m) in the River Thames, and remained there for over an hour and a half. Halley’s bell was of little use for practical salvage work, as it was very heavy, but he made improvements to it over time, later extending his underwater exposure time to over 4 hours. Halley suffered one of the earliest recorded cases of middle ear barotrauma. That same year, at a meeting of the Royal Society, Halley introduced a rudimentary working model of a magnetic compass using a liquid-filled housing to damp the swing and wobble of the magnetized needle.

In 1691, Halley sought the post of Savilian Professor of Astronomy at Oxford. While a candidate for the position, Halley faced the animosity of the Astronomer Royal, John Flamsteed, and his religious views were questioned. His candidacy was opposed by both the Archbishop of Canterbury, John Tillotson, and Bishop Stillingfleet, and the post went instead to David Gregory, who had the support of Isaac Newton.

In 1692, Halley put forth the idea of a hollow Earth consisting of a shell about 500 miles (800 km) thick, two inner concentric shells and an innermost core. He suggested that atmospheres separated these shells, and that each shell had its own magnetic poles, with each sphere rotating at a different speed. Halley proposed this scheme to explain anomalous compass readings. He envisaged each inner region as having an atmosphere and being luminous (and possibly inhabited), and speculated that escaping gas caused the Aurora Borealis. He suggested, “Auroral rays are due to particles, which are affected by the magnetic field, the rays parallel to Earth’s magnetic field.”

In 1693 Halley published an article on life annuities, which featured an analysis of age-at-death on the basis of the Breslau statistics Caspar Neumann had been able to provide. This article allowed the British government to sell life annuities at an appropriate price based on the age of the purchaser. Halley’s work strongly influenced the development of actuarial science. The construction of the life-table for Breslau, which followed more primitive work by John Graunt, is now seen as a major event in the history of demography.

In 1698, Halley was given command of the Paramour, a 52 feet (16 m) pink (sailing ship), so that he could carry out investigations in the South Atlantic into the laws governing the variation of the compass. On 19th August 1698, he took command of the ship and, in November 1698, sailed on what was the first purely scientific voyage by an English naval vessel. Unfortunately, problems of insubordination arose over questions of Halley’s competence to command a vessel. Halley returned the ship to England to bring charges against his officers in July 1699. The result was a mild rebuke for his men, and dissatisfaction for Halley, who felt the court had been too lenient. Halley thereafter received a temporary commission as a Captain in the Royal Navy, recommissioned the Paramour on 24th August 1699 and sailed again in September 1699 to make extensive observations on the conditions of terrestrial magnetism. He accomplished this task in a second Atlantic voyage which lasted until 6th September 1700, and extended from 52 degrees north to 52 degrees south. The results were published in General Chart of the Variation of the Compass (1701). This was the first such chart to be published and the first on which isogonic, or Halleyan, lines appeared.

In November 1703, Halley was appointed Savilian Professor of Geometry at the University of Oxford, his theological enemies, John Tillotson and Bishop Stillingfleet having died, and received an honorary degree of doctor of laws in 1710. In 1705, applying historical astronomy methods, he published Synopsis Astronomia Cometicae, which stated his belief that the comet sightings of 1456, 1531, 1607, and 1682 were of the same comet, which he predicted would return in 1758. Halley did not live to witness the comet’s return, but when it did, the comet became generally known as Halley’s Comet.

By 1706 Halley had learned Arabic and completed the translation started by Edward Bernard of Books V-VII of Apollonius’s Conics from copies found at Leiden and the Bodleian Library at Oxford. He also completed a new translation of the first four books from the original Greek that had been started by the late David Gregory. He published these along with his own reconstruction of Book VIII in the first complete Latin edition in 1710.

In 1716, Halley suggested a high-precision measurement of the distance between the Earth and the Sun by timing the transit of Venus. In doing so, he was following the method described by James Gregory in Optica Promota (in which the design of the Gregorian telescope is also described). It is reasonable to assume Halley possessed and had read this book given that the Gregorian design (a reflecting telescope) was the principal telescope design used in astronomy in Halley’s day. It is not to Halley’s credit that he failed to acknowledge Gregory’s priority in this matter. In 1718 he discovered the proper motion of the “fixed” stars by comparing his astrometric measurements with those given in Ptolemy’s Almagest. Arcturus and Sirius were two noted to have moved significantly, the latter having progressed 30 arc minutes (about the diameter of the moon) southwards in 1800 years.

In 1720, together with his friend the antiquarian William Stukeley, Halley participated in the first attempt to scientifically date Stonehenge. Assuming that the monument had been laid out using a magnetic compass, Stukeley and Halley attempted to calculate the perceived deviation introducing corrections from existing magnetic records, and suggested three dates (460 BCE, 220 CE and 920 CE), the earliest being the one accepted. These dates were wrong by thousands of years, but the idea that scientific methods could be used to date ancient monuments was revolutionary in its day.

Halley succeeded John Flamsteed in 1720 as Astronomer Royal, a position Halley held until his death. Halley died in 1742 at the age of 85. He was buried in the graveyard of the old church of St Margaret’s, Lee (since rebuilt), at Lee Terrace, Blackheath. He was interred in the same vault as the Astronomer Royal John Pond; the unmarked grave of the Astronomer Royal Nathaniel Bliss is nearby. His original tombstone was transferred by the Admiralty when the original Lee church was demolished and rebuilt – it can be seen today on the southern wall of the Camera Obscura at the Royal Observatory, Greenwich. His marked grave can be seen at St Margaret’s Church, Lee Terrace.

For no other reason than the name, I give you a recipe for hasty pudding from a manuscript dated 1742. Hasty pudding was popular in the 18th century because, as the name implies, it was a quick and easy dessert. In this case, I suspect that the second sentence means to add the flour and butter mix to boiling milk and continue cooking. Otherwise the flour would not cook, and that would be rather nasty. Actually, the whole affair seems pretty nasty to me, but I like the idea of celebrating a man who tracked comets – which return slooooooooooowly – with a recipe for something hasty.

Hasty Pudding (1742)

Break an egg into fine flour, and with your hand work up as much as you can into as stiff a paste as possible.  Add milk boiling, and put in a little salt, some rose water, or orange-flower water, a few drops put to your taste, some butter, and keep stirring all one way till it is thick as you would have it, pour it oute and when it is in the dishe stick it all over with littel bits of butter, and beaten cinnamon over.

Oct 062018

Euridice, an opera by Jacopo Peri, with additional music by Giulio Caccini is the oldest surviving opera, first performed in Florence on this date in 1600 at the Palazzo Pitti with Peri himself singing the role of Orfeo. An earlier opera by Peri, Dafne (1597), is now lost. The libretto by Ottavio Rinuccini is based on books X and XI of Ovid’s Metamorphoses which recount the story of the legendary musician Orpheus and his wife Euridice. Because Europe’s actual oldest opera is lost, this date is the best we can do for dating the genesis of modern opera. Euridice was created for the marriage of Henry IV of France and Maria de Medici.

At the premiere, many of the roles were filled by members of Caccini’s entourage, including his daughter Francesca Caccini. Peri composed all of the music for the first production, but owing to the integral involvement of Caccini and his performers, some of Peri’s music was finally replaced by that of Caccini. When Caccini discovered that Peri intended to publish the opera with the added Caccini pieces, he rushed to finish his own version of Euridice using the same libretto, and managed to have his published before Peri’s. In his preface, Peri notes that all of the music was completed by the date of the first performance earning his efforts the designation Prima Euridice.

In creating the music for Euridice, Peri envisioned a vocal style that is half sung and half spoken. For less dramatic parts he created vocal lines close to the style of spoken language set over a sustained accompaniment. For impassioned scenes he explored stronger and more rapid melodies with steadily changing harmonies. Peri’s critics have observed that within the score of Euridice, he created no musically remarkable examples of either. However, he did use ranges and widths of register, as well as frequency and power of cadences, to distinguish different characters and dramatic moods. The voice and accompaniment are carefully paced to emphasize the tension and release in the text. Rhythmic and melodic inflections in the vocal lines closely, almost scientifically, imitate dramatic speech. In addition, impassioned exclamations are set with unprepared dissonances and unexpected movements in the bass. This extract may serve to show the style of the piece. It is pleasant enough, but not remarkable musically.

Euridice has its detractors, but there is general agreement that Peri established sound principles for operatic composition. Classic opera, henceforth, tells a story that exploits the interplay between aria and recitative, and uses a mix of solo, ensemble and choral singing. Peri’s Euridice tells the story of the musician Orpheus and his wife Euridice based on classic Greek legend, but with allowances for artistic license. According to the legend (which is actually retold in a number of ancient texts in Latin), Orpheus was a great musician who journeyed to the underworld to plead with the gods to revive his wife Euridice after she had been fatally injured.

Act 1


The opera opens with a simple melody by a singer representing the Tragic Muse, La Tragedia, and a short ritornello. Shepherds nearby and the Tragic Muse sing a conversation in recitatives and choruses, Daphne enters to notify everyone that Euridice has been fatally bitten by a serpent.

Scene 1

All of the nymphs and shepherds gather to celebrate the wedding of Orfeo and Euridice.

Scene 2

Orfeo is content after his wedding but is soon interrupted by Dafne. She brings the terrible news that Euridice has been bitten by a venomous snake and has died. Orfeo then vows to rescue her from the underworld.

Scene 3

Arcetro recounts that while Orfeo lay weeping, Venus, goddess of love, carries him off in her chariot.

Act 2

This opens with Orpheus pleading with Venere, Plutone, Prosperina, Caronte, and Radamanto in the underworld for the return of his beloved wife Euridice. Nearly the entire scene is carried in recitative. When the act closes, Orpheus is back with Tirsi and the other shepherds.

Scene 4

Venus and Orfeo arrive at the gates of the underworld. Venus suggests that through his legendary voice he might persuade Pluto to return Euridice to life. Orfeo succeeds and is allowed to leave with his bride.

Scene 5

Orfeo and Euridice return from the underworld and rejoice.

The entire opera, with libretto in Italian with an English translation, is here: 

If you know the story of Orpheus and Eurydice you will know that the ending of the opera does not coincide with the Greek legend. In the original, Hades allows Orpheus to take Eurydice back but she is still a “shade” until she reaches the sunlight and gains human form again, and Orpheus must not look back until she is in the sunlight. Because she does not have a body, when she walks behind Orpheus she does not make any sound, and Orpheus, fearing he has been tricked by Hades looks back just before he reaches the surface to check she is there, and she is taken back to the Underworld. Lesson #1 people – HAVE FAITH.

Today’s recipe is for a version of pasta in brodo from the cookery book Opera (first published 1570from Bartolomeo Scappi, who was active from 1536 to 1570 – the period of this opera. I chose it, partly because it is contemporary Italian, partly because I am a fan of pasta in brodo, and partly because of the coincidence of names (“opera” in the book’s title means “works” or “actions”). Note that the soup can be made with broth or milk and that the seasonings include sugar and cinnamon. By all means boil up a crane or hare to make your broth.


Per far minestra di tagliatelli

Impastinosi due libre di fior di farina con tre uoua, & acqua tepida, & mescolisi bene sopra una tavola per lo spatio d’un quarto d’hora, & dapoi stendasi sottilmente con il bastone, & lascisi alquanto risciugare il sfoglio, & rimondinosi con lo sperone le parti piu grosse, che son gli orlicci, & quando sarà asciutto però non troppo, perche crepe rebbe, spoluerizzisi di fior di farina con il fetaccio, accioche non si attacchi, piglisi poi il bastone della pasta, & comincisi da un capo, & riuolgasi tutto lo sfoglio sopra il bastone leggiermente, cauisi il bastone, e taglisi lo sfoglio cosi riuolto per lo trauerso con un coltello largo sottile, e tagliati che saranno, slarghinosi, & lassinosi alquanto rasciugare, & asciutti che saranno, fettaccisi fuora per lo criuello il farinaccio, & facciasene minestra con brodo grasso di carne, o con latte, & butiro, & cotti che saranno, seruanosi caldi con cascio, zuccaro, & cannella, & uolendone far lasagne taglisi la pasta sul bastone per lungo, & compartasi la detta pasta in due parti parimente per lungo, e taglisi in quadretti, & faccianosi  cuocere in brodo di lepre, ouero di grua, o d’altra carna, o latte, & seruanosi calde con cascio, zuccaro, & cannella.

To prepare soup with tagliatelle
Work two pounds of flour, three eggs and warm water into a dough, kneading it on a table for a quarter of an hour. Roll it out thin with a rolling pin and let the sheet of dough dry a little. Trim away the irregular parts, the fringes, with a cutting wheel. When it has dried, though not too much because it will break up, sprinkle it with flour through a sieve so it will not stick. Then take the rolling pin and, beginning at one end, wrap the whole sheet loosely on to the pin, draw the pin out and cut the rolled-up dough crosswise with a broad, thin knife. When they are cut, flatten them. Let them dry out a little and, when they are dry, shake off the excess flour through a sieve. Make a soup of them with a fat meat broth, or milk and butter. When they are cooked, serve them hot with cheese, sugar and cinnamon. If you want to make lasagnas of them, cut the dough lengthwise on the pin, and likewise divide it lengthwise in two, and cut that into little squares. Cook them in the broth of a hare, a crane or some other meat, or in milk. Serve them hot with cheese, sugar and cinnamon.



Aug 232013


Today is the Vulcanalia, the ancient celebration of the god Vulcan in the Roman pantheon.  Vulcan was the son of Jupiter and Juno, and brother of Mars. He is the god of fire, including the fire of volcanoes , and the god of craftsmen who use fire, such as blacksmiths.  He is often depicted as a craftsman with a hammer and forge.  He has analogs in many ancient cultures, including Greece and Egypt, so tales about him are often muddled and contradictory.  Here’s my pastiche that accords with some of the threads. In all the tales he is depicted as deformed and brutal (especially in his sexuality), yet capable of producing the most wondrous things – thrones for the gods, exquisite jewelry, and powerful weapons.  As such he represents the twin aspects of fire: production and destruction.  All cooks know this about fire!!!

Vulcan was the son of Jupiter and Juno.  He was so ugly at birth that Juno flung him from Mt Olympus in disgust.  He fell for a day and a night, landing in the sea and breaking his leg in the fall. Ever after he had a limp.  Vulcan sank to the depths where the sea-nymph, Thetis, found him and took him to her underwater grotto, raising him as her own son. Vulcan had a happy childhood with dolphins as his playmates and pearls as his toys. Late in his childhood, he found the remains of a fisherman’s fire on the beach and became fascinated with an unextinguished coal, still red-hot and glowing.

Vulcan carefully shut this precious coal in a clamshell and took it back to his underwater grotto and made a fire with it. On the first day after, Vulcan stared at this fire for hours on end. On the second day, he discovered that when he made the fire hotter with bellows, certain stones gave up metals: iron, silver, and gold. On the third day he beat the cooled metals into shapes: bracelets, chains, swords and shields. Vulcan made pearl-handled knives and spoons for his foster mother, he made a silver chariot for himself, and bridles so that seahorses could transport him quickly. He even made slave-girls of gold to wait on him and do his bidding.


At one point, Thetis left her underwater grotto to attend a dinner party on Mount Olympus wearing a beautiful necklace of silver and sapphires, which Vulcan had made for her. Juno admired the necklace and asked where she could get one. Thetis became flustered causing Juno to become suspicious and, at last, the queen god discovered the truth: the baby she had once rejected had grown into a talented artisan. Juno was furious and demanded that Vulcan return home. He refused. However he did send Juno a beautifully constructed chair made of silver and gold, inlaid with mother-of-pearl. Juno was delighted with this gift, but as soon as she sat in it her weight triggered hidden springs and metal bands that sprung forth to hold her fast. The more she shrieked and struggled the more firmly the mechanical throne gripped her. For three days Juno sat fuming, still trapped in Vulcan’s chair. She could not sleep, she could not stretch, she could not eat. This was Vulcan’s revenge for her rejection.

Jupiter finally saved Juno by promising Vulcan that if he released her, he would give him a wife, Venus the goddess of love and beauty. Vulcan agreed and married Venus. He later built a smithy under Mount Etna on the island of Sicily. It was said that whenever Venus is unfaithful (usually with Vulcan’s brother, Mars), Vulcan grows angry and beats the red-hot metal with such a force that sparks and smoke rise up from the top of the mountain, to create a volcanic eruption. Having ascended Etna during a particularly active period I can understand the origin of this tale. You can see the lava flows in pictures, but no one tells you about the noise. As rocks fly out of the cone there is an almost deafening banging like the hammering of a god on his forge.

Mt Etna

Mt Etna

With the assistance of the Cyclops, Vulcan made Jupiter fresh thunderbolts when the old ones decayed. He also made a helmet for Pluto, which rendered him invisible and a trident for Neptune, which shook both land and sea. At the request of Thetis he fabricated the divine armor of Achilles (her son), whose shield is so beautifully described by Homer, and also the invincible armor of Aeneas, at the entreaty of Venus. These tales may well be Greek and Roman versions of the same story.

Thetis Accepting the Shield of Achilles from Vulcan circa 1710 by Sir James Thornhill 1675 or 76-1734

When Jupiter was angry at mortals for stealing fire he requested a special revenge from the gods.  Vulcan fashioned Pandora out of clay, and Jupiter gave her the secret box that was not to be opened. You know what happens when you tell humans not to do something.


It was the custom in the Roman Empire, after gaining a victory in war, to pile the arms of the enemy in a heap on the field of battle, and make a sacrifice of them to Vulcan. His principal temple was in a consecrated grove at the foot of mount Etna, in which a fire continually burnt. According to legend, Romulus built Vulcan a temple outside the walls of the city, the augurs being of the opinion that the god of fire ought not to be admitted within the city. But in historic times he had two temples within Rome, one of which was used as a meeting house when Rome was in grave danger.

Vulcanalia was part of a cycle of four agricultural festivities in the second half of August (Consualia on August 21st, Vulcanalia on 23rd, Opiconsivia on 25th, and Volturnalia on 27th). Two of them, Consualia and Opiconsivia, concerned the blessing of harvesting and storing grain, and two, Vulcania and Volturnalia, concerned threats to the harvest, fire and flood respectively.  Almost nothing is known about how the Vulcanalia was celebrated except that bonfires were lit outside the city and small animals were sacrificed and eaten.  It is also said that farmers began their work by candlelight on that morning.


According to some ancient sources the first intimations of the eruption of Vesuvius that destroyed Pompeii, began on the Vulcanalia of 79 CE, although it is now impossible to date the event precisely.  Maybe this was no more than poetic license on the part of early historians.  Nonetheless I will take this fanciful historical note as an excuse for my recipe of the day, Chicken Vesuvius. This is a Neapolitan dish, but is rather unusual in that it uses potatoes for the starch rather than pasta. Peas are the most common vegetable, but I am partial to artichoke hearts.


Chicken Vesuvius


3 tbsps extra virgin olive oil
1 2 lb (1 kilo) chicken
salt and freshly ground black pepper
1 ½ lbs (750 g) small red-skinned potatoes, halved
4 large garlic cloves, peeled and minced
¾ cup dry white wine
¾ cup chicken broth
1 ½ tsps dried oregano
1 tsp dried thyme
1 cup peas (or 8 oz artichoke hearts quartered)
2 tbsps unsalted butter


Preheat the oven to 450°F/230°C.

Cut the chicken into 8 pieces (2 thighs, 2 drumsticks, 4 breast pieces). Season with salt and freshly ground black pepper.

Heat the olive oil in a dutch oven over high heat.

Working in batches, sauté the chicken until golden on all sides.  Transfer the pieces to a bowl when browned.

Add the potatoes to the pot and sauté until they are golden brown. Add the garlic and sauté for 1 minute. Do not let it take on color.

Add the wine and stir to scrape up any brown bits on the bottom of the pot.

Add the broth, oregano, and thyme. Return the chicken to the pot. Stir to combine. Bring to a boil over medium-high heat.

Cover and bake in the oven until the chicken is cooked through, about 20 minutes.

Transfer the chicken to a platter. Arrange the potatoes around chicken. Keep warm.

Add the peas (or artichoke hearts) to the sauce in the pot. Cover and simmer over high heat until the peas are cooked, stirring often, about 4 minutes. Turn heat to low. Stir in the butter. Pour the sauce over chicken and potatoes, and serve.

Serves 4